Electrochemical synthesis and characterization of basic bismuth nitrate [Bi6O5(OH)3](NO3)5·2H2O: a potential highly efficient sorbent for textile reactive dye removal

A new method of synthesis was developed for the preparation of basic bismuth nitrate [Bi6O5(OH)3](NO3)5·2H2O (ECBBN). Electrochemical synthesis of the material was carried out by galvanostatic electrodeposition from an acidic Bi(III) solution on a Ti substrate and further thermal treatment in air at 200 °C. Characterization of ECBBN was conducted by employing SEM–EDX, N2 adsorption, XRD and FTIR, and its pI was also determined. The analyses showed that the material obtained was pure [Bi6O5(OH)3](NO3)5·2H2O. Morphologically, ECBBN aggregates were composed of crystals, some smaller than 50 nm. Electrochemically synthesized sorbent (ECBBN) was used for the removal of the textile dye Reactive Blue 19 (RB19) from deionized water and model solutions of polluted river water, and it showed considerably superior sorption performance compared to other inorganic sorbents synthesized by conventional methods reported in the literature. A kinetic study suggests that the sorption process is both under reaction and diffusion control. Equilibration of the sorption process was attained in several minutes, i.e. the sorption process is very fast. The sorption equilibrium data were well interpreted by the Langmuir, Redlich–Peterson and Brouers–Sotolongo isotherm. Using Langmuir isotherm, the maximum sorption capacity of ECBBN was reached at pH 2 and was 1049.19 mg g−1

Leaching of chromium from chromium contaminated soil: Speciation study and geochemical modeling

Distribution of chromium between soil and leachate was monitored. A natural process of percolating rainwater through the soil was simulated in the laboratory conditions and studied with column leaching extraction. Migration of chromium in the soil is conditioned by the level of chromium soil contamination, the soil organic matter content, and rainwater acidity. Chromium (III) and chromium(VI) were determined by spectrophotometric method with diphenilcarbazide in acidic media. Comparing the results of chromium speciation in leachate obtained by experimental model systems and geochemical modelling calculations using Visual MINTEQ model, a correlation was observed regarding the influence of the tested parameters. Leachate solutions showed that the concentration of Cr depended on the organic matter content. The influence of pH and soil organic matter content is in compliance after its definition through experimental and theoretical way. The computer model - Stockholm Humic Model used to evaluate the leaching results corresponded rather well with the measured values

Synthesis and characterization of new Ti–Bi2O3 anode and its use for reactive dye degradation

This paper reports the synthesis, characterization and application of a Ti–Bi2O3 anode for the electrochemical decolorization of the textile dye Reactive Red 2. The anode was synthesized by electrodeposition on a Ti substrate immersed in an acidic bismuth (III) solution at constant potential, followed by calcination in air at 600 °C. Thermogravimetric Analysis (TGA), Energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analysis revealed that the electrodeposited material was predominantly metallic bismuth, which was oxidized to pure α-Bi2O3 during the calcination in air. SEM micrographs revealed that the Bi2O3 coat at the anode surface was inhomogeneous and porous. Reactive Red 2 was completely electrochemically decolorized at the synthesized anode in the presence of H2O2. The applied current density, H2O2 and Na2SO4 concentration, medium pH and initial dye concentration affected the dye decolorization rate. The optimal process parameters were found to be as follows: an applied current density of 40 mA cm−2 using a mixture of 10 mmol dm−3 H2O2 and 10 mmol dm−3 Na2SO4 at pH 7. The dye decolorization rate was shown to decrease as its initial concentration increased. The decolorization reactions were found to follow pseudo-first order kinetics

The biosorption potential of waste biomass young fruit walnuts for lead ions: Kinetic and equilibrium study

The biosorption potential of waste biomass young fruit walnuts (YFW) as a low-cost biosorbent, processed from liqueur industry, for Pb(II) ions from aqueous solution was explored. The structural features of the biosorbent were characterized by FTIR spectroscopy, which indicates the possibility that the different functional groups may be responsible for the binding of Pb(II) ions from aqueous solution. The effects of relevant parameters such as pH (2 - 6), contact time (0 - 120 min), biosorbent dosage (2 - 20 g), initial metal ion concentration (10 - 120 mg dm-3), at a temperature of 25(C with stirring (120 rpm) and a constant ionic strength of 0,02 mol dm-3 were evaluated in batch experiments. The sorption equilibrium of Pb(II) ion (when 84 % of metal ions were sorbed at an initial concentration of 15 mg dm-3) was achieved within the pH range 4 - 5 after 50 min. Kinetic data were best described by the pseudo-second order model. Removal efficiency of Pb(II) ion rapidly increased with increasing biosorbent dose from 2.0 to 8.0 g per dm-3 of sorbate. Optimal biosorbent dose was set to 6.0 g per dm3 of sorbate. An increase in the initial metal concentration increases the biosorption capacity. The sorption data of investigated metal ion are fitted to Langmuir, Freundlich and Temkin isotherm models. The equilibrium data were well fitted by the Langmuir isotherm model (R2 ≥ 0.990). The maximum monolayer biosorption capacity of waste biomass YFW for Pb(II) ion, at 25.0 ± 0.5°C and pH 4.5, was found to be 19.23 mgg-1. This available waste biomass is efficient in the uptake of Pb(II) ions from aqueous solution and could be used as a low-cost and an alternative biosorbent for the treatment of wastewater streams bearing these metal ions

Analytical application of the reaction system methylene blue B-K2S2O8 for the spectrophotometric kinetic determination of silver in citric buffer media

A new, simple, rapid, sensitive and selective spectrophotometric kinetic method for Ag(I) traces determination at room temperature was elaborated in this paper. It is based on catalytic effect of silver ions upon the oxidation of methylene blue B (MBB) by K2S2O8 (PPS) in citric buffer (BUF) solution. The method was confirmed by determination of Ag(I) in PbO. The obtained results were compared to those obtained by ICP-OES method and good agreement of results was found. [Projekat Ministarstva nauke Republike Srbije, br. 172051

KARAKTERIZACIJA MODIFIKOVANIH BIOSORBENATA POMOĆU TIO2 I NJIHOVA PRIMENA ZA UKLANJANJE JONA TEŠKIH METALA

Preparation, characterization and application of materials modified with TiO2 nanoparticle have been reviewed. Chitosan, bacterial biomass and dendrimers were the starting material for modification. Sorbents characterization was performed by scanning electron microscopy (SEM). In order to investigate the sorption capabilities of sorbents, we used them for removal of heavy metal ions from aqueous solution. The effect of contact time on heavy metal ions sorption and maximum sorption capacities of biosorbents are shown. As a very important parameter of the sorption process, the effect of initial pH values on heavy metal removal was examined. This paper indicates that sorption using the material modified with TiO2 is becoming a promising alternative to conventional adsorbents in removing heavy metal ions.U ovom radu je predstavljen pregled dobijanja, karakterizacije i primene materija modifikovanih pomoću TiO2 . Kao početni material za modifikaciju korišćeni su citozan, bakterijska biomasa i dendrimeri. Karakterizacija dobijenih sorbenata je rađena primenom skenirajuće elektronske mikroskopije (SEM). Sorbenti su korišćeni za uklanjanje jona teških metala iz vodenih rastvora, u cilju ispitivanja njihovih sorpcione sposobnosti. Prikazan je uticaj kontaktnog vremena na uklanjanje jona teških metala i maksimalni sorpcioni kapacitet biosorbenata. Ispitivan je uticaj inicijalnog pH rastvora na uklanjanje jona teških metala, kao jedan od najbitnijih faktora koji utiče na sorpcioni proces. Rezultati pokazuju da se biosorbenti modifikovani sa TiO2 mogu koristiti kao efikasno sredstvo za uklanjanje jona teških metala iz vode

Removal of copper(II) ion from aqueous solution by high-porosity activated carbon

The removal of copper(II) ion from aqueous solution by the granular activated carbon, obtained from hazelnut shells (ACHS) (Corylus avellana L. var. lunga istriana), was investigated. The ACHS was prepared from ground dried hazelnut shells by specific method carbonisation and water steam activation at 950 degrees C for 2 h. The granular activated carbon produced from hazelnut shells has a high specific surface area (1 452 m(2).g(-1)) and highly developed microporous structure (micropore volume: 0.615 cm(3).g(-1)). In batch tests, the influences of solution pH, contact time, initial metal ion concentration and temperature on the sorption of copper(II) ion on ACHS were studied. The results indicate that sorption of copper(II) ion on ACHS strongly depends on pH values. The adsorption data can be well described by the Langmuir isotherm and Redlich-Peterson model. The monolayer adsorption capacity of the ACHS-copper(II) ion, calculated from the Langmuir isotherms, is 3.07 mmol.g(-1). The time-dependent adsorption of copper(II) ion could be described by the pseudo second-order and Elovich kinetics, indicating that the rate-limiting step might be a chemical reaction. The intra-particle diffusion model indicates that adsorption of copper(II) ions on ACHS was diffusion controlled

Application of new biosorbent based on chemicaly modified Lagenaria vulgaris shell for the removal of copper(II) from aqueous solutions: Effects of operational parameters

In present study a low cost biosorbent derived from Lagenaria vulgaris plant by xanthation, was tested for its ability to remove copper from aqueous solution. The effect of contact time, initial pH, initial concentration of copper(II) ions and adsorbent dosage on the removal efficiency were studied in a batch process mode. The optimal pH for investigated metal was 5. A dosage of 4 g dm-3 of xanthated Lagenaria vulgaris biosorbent (xLVB) was found to be effective for maximum uptake of copper(II). The kinetic of sorption of metal was fast, reaching at equilibrium in 50 min. The kinetic data were found to follow closely the pseudo-second-order model. The adsorption equilibrium was described well by the Langmuir isotherm model with maximum adsorption capacity of 23.18 mg g-1 copper(II) ions on xLVB. The presence of sulfur groups on xLVB were identified by FTIR spectroscopic study. Copper removal efficiency was achieved at 81.35% from copper plating industry wastevater

Removal of copper(II) ion from aqueous solution by high-porosity activated carbon

The removal of copper(II) ion from aqueous solution by the granular activated carbon, obtained from hazelnut shells (ACHS) (Corylus avellana L. var. lunga istriana), was investigated. The ACHS was prepared from ground dried hazelnut shells by specific method carbonisation and water steam activation at 950 degrees C for 2 h. The granular activated carbon produced from hazelnut shells has a high specific surface area (1 452 m(2).g(-1)) and highly developed microporous structure (micropore volume: 0.615 cm(3).g(-1)). In batch tests, the influences of solution pH, contact time, initial metal ion concentration and temperature on the sorption of copper(II) ion on ACHS were studied. The results indicate that sorption of copper(II) ion on ACHS strongly depends on pH values. The adsorption data can be well described by the Langmuir isotherm and Redlich-Peterson model. The monolayer adsorption capacity of the ACHS-copper(II) ion, calculated from the Langmuir isotherms, is 3.07 mmol.g(-1). The time-dependent adsorption of copper(II) ion could be described by the pseudo second-order and Elovich kinetics, indicating that the rate-limiting step might be a chemical reaction. The intra-particle diffusion model indicates that adsorption of copper(II) ions on ACHS was diffusion controlled

Experimental and modelling study on strontium removal from aqueous solutions by Lagenaria vulgaris biosorbent

The shell of Lagenaria vulgaris (LV) plant was used as biosorbent for strontium removal from aqueous solutions. Chemical structure of the biosorbent's surface was characterized by the means of FTIR and Boehm's titrations. SEM-EDX technique was used to study the morphology and elemental composition of the material. The analyses pointed out to abundance of acidic functional groups which are charged in solution and hence responsible for ionic exchange of Sr(II) ions. Sorption was examined by varying initial concentrations of Sr(II) in solutions, sorbent's loadings, pH, and contacting times. Equilibrium of the process was attained in the first 10 min of contacting and followed pseudo-second order and Chrastil's kinetic models. It was established that sorption onto aLVB was heterogenous by nature and fitted well to Freundlich and Sips isotherm models with maximum sorption capacity of 29.55 mg g(-1). Sorption potentail was kept high after six cycles when acidic desorbents were used